From the Third Meditation onwards, Descartes’ statements are puzzling to his readers.
On the one hand, he claims that “certainty and truth of all knowledge [scientiae] depends uniquely on my awareness [cognitione] of the true God, to such an extent that I was incapa-ble of perfect knowledge [perfecte scire] about anything else until I became aware of him”
(CSM II 49 / AT VII 71). However, on the other hand, he still relies on a “clear and distinct idea of (…) God” (CSM II 37 / AT VII 53) as well as on the assumption that “it is manifest by the natural light that there must be at least as much reality in the efficient and total cause as in the effect of that cause” (CSM II 28 / AT VII 40) in order to demonstrate God’s existence. Therefore, it is not surprising that Arnauld, one of Descartes’ contemporaries, highlighted a problem of circularity (see AT VII 124–125 / CSM II 88–89). Formally construed, if P is the proposition “What one clearly and distinctly perceives is true”, and Q is the proposition “God exists”, Descartes’ argument (extracted from the above quotations) seems to embrace both claims:
(1) K(P) → K(Q) One knows P only if one first knows Q.
(2) K(Q) → K(P) One knows Q only if one first knows P.
Hence, Descartes’ aim to justify P and Q seems to fail, since (1) and (2) are caught in a circle and therefore cannot justify either P or Q.
Weighty as this accusation appears, Descartes himself was nevertheless quite unim-pressed and replied:
when I said that we can know [scire] nothing for certain until we are aware that God exists, I expressly declared that I was speaking only of knowledge [scientia]
of those conclusions which can be recalled when we are no longer attending to the arguments by means of which we deduced them. Now awareness [notitia] of first principles is not normally called ‘knowledge’ [scientia] by dialecticians. When some-one says “I am thinking, therefore I am, or I exist”, he does not deduce existence from thought by means of a syllogism, but recognizes it as something self-evident by
a simple intuition of the mind [per se notam simplici mentis intuitu agnoscit] (CSM II 100 / AT VII 140. Emphasis added).
I made a distinction between what we in fact perceive clearly and what we remember having perceived clearly on a previous occasion. To begin with, we are sure that God exists because we attend to the arguments which prove this; but subsequently it is enough for us to remember that we perceived something clearly in order for us to be certain that it is true. This would not be sufficient if we did not know [sciremus]
that God exists and is not a deceiver (CSM II 171 / AT VII 246. Emphasis added).
Descartes admits that before the demonstration of God’s existence he does not possess any “knowledge”, that which he calls “scientia”, or denotes with the verb “scire”. However, what he can rely on is what he calls “notitia”, “mentis intuitu[s]” and later on several times – which becomes the central term – “cogitatio”. Descartes considers scientia to be a body of knowledge, as something which is stable and exists over time. Cogitatio in contrast means single flashes of perceptions without temporal extension in any way. Rather, cogitatio is restricted to the instantaneous moment of being thought or perceived. As Descartes said, it lasts “quandiu cogito” (AT VII 27 / CSM II 18).1
Descartes’ reply contains two crucial distinctions: Firstly, Descartes distinguishes be-tween present clear and distinct perceptions and past clear and distinct perceptions (respec-tively between single present and clear perceptions, and the general link between clear and distinct perceptions and truth).2 Secondly, he argues that different epistemic relations apply to present and past perceptions, namely cogitatio and scientia.
On the basis of these distinctions, Descartes claims that in his demonstration of God’s existence he employed only present clear and distinct perceptions which are encountered through cogitatio and are not devoid of justificatory potential on their own. They are “self-evident”, and as such are reliable premises in his demonstration.
It is important to note that Descartes does not hold that there is a certain class of (present) perceptions which can always be recognised as true while other present percep-tions cannot. He only claims that at the moment when he perceives something clearly and distinctly (without further qualification of what this “something” is about), he can be in-stantly assured of its truth.3 However, it would be false to say that the Cartesian Meditator knows that “whatever he presently clearly and distinctly perceives is true” from the outset.
1 See also AT VII 25 (CSM II 17) where Descartes uses the word “quoties”.
2 For the purpose of this paper I do not need to decide whether the so-called Memory Defence which Doney (1955) argued for, or whether the so-called General Link Defence, which Frankfurt (1970), Kenny (1970), Van Cleve (1979) argued for, is correct.
3 Nelson (1964), Broughton (1984), and Cottingham (1998) nevertheless assume that there is a class of demon-proof perceptions. However, only according to my temporal interpretation, which is similarly advocated by Gerwirtz (1941) and Della Rocca (2005), can one make sense of Descartes saying both that all perceptions are subject to doubt (AT VII 21 / CSM II 21), and that nevertheless some percep-tions are not subject to doubt (see Descartes’ aforementioned reply). Whether something is subject to doubt depends on whether it is before one’s mind (as a clear and distinct perception) at a given moment.
He does not claim any such second-order knowledge about the truth of present percep-tions like K(P). Nevertheless, there is still an ongoing debate on luminosity here, namely, whether the Cartesian Meditator has to be at least aware that he is currently perceiving something clearly and distinctly, or whether just the act of perceiving something clearly and distinctly is sufficient to be aware of its truth (See Van Cleve 1979, 66–74).
A few further clarifying comments on Descartes’ notion of “clear and distinct percep-tion” may be required.
Firstly, Descartes seems to embrace a strong kind of internalism. Defining a clear and distinct perception in the Principles, he says that a perception is clear when it is “present and accessible to the attentive mind”(Principles, Part I, 45. CSM I 207 / AT VIIIA 22) and distinct when “it is so sharply separated from all other perceptions that it contains within itself only what is clear” (Principles, Part I, 45. CSM I 208 / AT VIIIA 22). Thus, the grounds for both clearness and distinctness arise only from within the Meditator’s perspec-tive. The question as to whether this account presents a genuinely epistemic internalism remains, however, to be seen.
Secondly, a clear and distinct perception is an intellectual presentation of something being so-and-so without being identical to believing. Not only does Descartes repeatedly talk about cases in which he used to believe something but nevertheless did not clearly and distinctly perceive it, a clear and distinct perception is also considered a state of mind which – if it occurs – is prior to believing. This point was made clear in the Discourse when Descartes formulated his goal in the following way: “to include nothing more in my judge-ment than what presented itself to my mind so clearly and distinctly that I had no occasion to doubt it” (CSM I 120 / AT VI 18).4 Saying that something “presented itself (…) so (…) that” indicates the logical order. Adopting a belief is subsequent to the evaluation of clear-ness and distinctclear-ness, no matter how quickly the transition may happen and no matter how compelled one feels to adopt the belief when facing a clear and distinct perception.
This very transition from clearly and distinctly perceiving to believing will be discussed in the next section.
Lastly, it is worth being aware that Descartes was not clear on whether propositions5 or ideas (for instance AT VII 53 / CSM II 37) are the object of clear and distinct perceptions, nor was he clear on whether it is the perception (Principles Part I, 30, 45–46: AT VIIIA 17, 22 / CSM I 203, 207–208) that is clear and distinct or the proposition/idea (AT VII 46 / CSM II 31–32).For the rest of the paper, I will not draw sharp distinctions between these different possibilities but rather assume that the idea of God and respectively the proposi-tion “God exists” are such that one can clearly and distinctly perceive it.
To come back to Arnauld’s objection: if Descartes is entitled to claim that a present clear and distinct perception is justified in its own right, he can successfully refute the ac-cusation of circularity. The proof of God’s existence is not required for the validity of
cogi-4 The original reads as follows: “si clairement et si distinctement (…) que je n’eusse aucune occasion de le mettre en doute”.
5 For instance AT VII 35 (CSM II 25): “sum certus me esse rem cogitantem”. I take the grammatical structure to indicate a proposition here. See also AT VI 32–33 / CSM I 127.
tationes that are used as premises. The proof is only required for facilitating the transition from “cogitatio” to “scientia” and thereby creating a stable body of knowledge out of these single and disconnected flashes of perceptions. However, Descartes’ stance is unsatisfac-tory in the sense that it significantly begs the unanswered question: how can one be assured of the truth of present clear and distinct perceptions in the first place? This is where the discussion on the Cartesian Circle reaches its peak.